Fix IPv6 examples in t_client.rc-sample

IPv6 documentation prefix is 2001:db*8*:: (not :dba:), and the second
test stanza variables need to end in _2, of course...

Signed-off-by: Gert Doering <gert@greenie.muc.de>
Acked-by: Josh Cepek <josh.cepek@usa.net>
Message-Id: <1384624401-27943-1-git-send-email-gert@greenie.muc.de>
URL: http://article.gmane.org/gmane.network.openvpn.devel/7992
(cherry picked from commit bbc3a6473c84ba7cdb87b359f016cd13773e42ec)